1. Field of Invention
This invention relates to the field of media management. More particularly, this invention relates to a system and method for the storage and retrieval of off-line preformatted optical disk cartridges.
2. General Background
Management of off-line media has been proposed in the area of magnetic media such as 4 MM or 8 MM cassettes. One such proposal involves the affixation of sequentially-numbered coded labels to the outside of the cassette cartridges. As seen in FIG. 1, the label 10 generally includes two parts: a first part including an alphanumeric code 20 unique to the particular cassette, and a second part including a bar code 30 adjacent to the alphanumeric code 20. Under this proposal, each time a new cassette is ordered or consumed, the alphanumeric code 20 is incremented and a label including this incremented code is affixed to the new cassette. The bar code 30 adjacent to the alphanumeric code 20 may be scanned with a bar code scanner (not shown), to generate an electrical signal representing the alphanumeric code 20. This signal is generally provided to a decoding device, and the decoded signal is stored in data storage e.g., as part of an inventory, list. In this manner, the user can keep track of the cassettes used or consumed. Furthermore, the cassette cartridges can be stored in a storage area according to their respective sequentially-numbered codes. The labels can be color-coded so that a particular cassette cartridge can be readily identified by simple visual inspection.
More recently, as the requirements for access to larger amounts of data and other information increases, there is a concomitant demand for more flexible, expandable mass storage. Magneto-optical and oliver erasable optical disks have become increasingly popular for storing data, given that substantial amount of information may be stored in digital format in these high density disks, information may be readily written to and erased or read from these disks, and such disks are generally impervious to stray magnetic fields at room temperatures. In light of the aforementioned advantages, erasable optical disks have become particularly popular with users who require substantial libraries of cataloged information. For example, sales and marketing departments may use such disks in order to store catalogs of financial data, graphics, and other information.
In addition, optical disk cartridge storage and retrieval devices have been proposed which allow for the storage and retrieval of any of a preselected number of erasable optical disk cartridges. One such optical disk cartridge storage and retrieval device is the OSL-2000, which is commercially available from Sony Electronics Inc., 1 Sony Drive, Park Ridge, N.J. 07656, and which may be seen with reference to FIGS. 3a and 3b. Optical disk cartridge storage and retrieval devices may be dedicated to a computer or may be connected to several workstations via a computer network such as a local area network (LAN) or wide are network (WAN) . The following description relates to a network-enabled optical disk cartridge storage and retrieval device; however, it will be understood that the following description is substantially applicable to that of an optical disk cartridge storage and retrieval device dedicated to a single computer.
Referring to FIGS. 3a and 3b, it will be seen that the network-enabled optical storage and retrieval device 40 preferably includes two components: a control system or controller 42 and the optical storage and retrieval device 43 itself. The controller 42 preferably includes a CPU, memory (preferably EPROM and RAM), a disk controller (e.g., an SCSI disk controller), and a network interface (not shown). In addition, the controller 42 contains a hard disk drive (not shown) for holding software, including executable programs and an operating system, and for serving as a cache for reading and writing accesses to increase information transfer to and from the optical disks encased by the optical disk cartridges. The hard disk drive also can maintain directory, pointers to all optical disk cartridges, including those stored off-line. The network-enabled optical disk cartridge storage and retrieval device 40 is connected at 49 to a LAN or WAN and acts as a server to provide storage resources to remote workstations connected to the network, and to allow these workstations to access information stored on the erasable optical disks contained in the optical storage and retrieval device 43.
The optical storage and retrieval device 43 stores up to, for example, twenty optical disk cartridges (not shown) in one or more racks in an array of horizontally-oriented storage slots 46. These storage slots are arranged in one or more vertical columns so that the optical disk cartridges sit horizontally one on top of another in the individual slots 46. A cartridge retrieval arm or mechanism 45 which is movable to a position adjacent one of such slots 46, is then activated to retrieve a selected disk 48 for reading/writing/erasing upon command from, and under the control of, either a central microprocessor located within the device or under the control of an external controller connected thereto. Read/write operations occur via a laser light beam imparted on the optical disk through an aperture in the optical disk cartridge. Cartridges stored in the device and retrievable by the cartridge retrieval arm or mechanism 45, are deemed "near-line", since they may be readily placed "on-line" via the cartridge retrieval arm or mechanism 45. The optical disk cartridges may be exchanged by ejection of a particular cartridge and insertion of another cartridge through a "mail" slot 44 in the device. These optical disk cartridge storage and retrieval devices are commonly referred to as "jukeboxes", given their similarity to the mechanical devices used for playing audio recordings popularized in the 1930's.
In operation, a workstation (not shown) connected to the network will send a request to access information from one of the optical disk cartridges which may be stored either near-line in the network-enabled optical storage and retrieval device 40, or off-line in storage. The request to access data is generally made by a "volume" or "media" ID. This media ID constitutes a name assigned to any number of optical disk cartridges associated by the type of information stored on the optical disks encased by the cartridges. For example, if one were using the network-enabled optical storage and retrieval device in the sales and marketing area, one media ID might be associated with three disk cartridges including competitors sales information, while a separate media ID might be associated with five disk cartridges including invoices, expense reports, and general accounting information. Because the network-enabled optical storage and retrieval device 40 maintains a list of the status of disk cartridges including those which are off-line, and a media ID can be associated with a limitless number of these optical disk cartridges, new disk cartridges can be readily added to an already existing group of optical disk cartridges associated with a particular media ID. The effect is to give the workstation user unlimited storage capacity for the particular data or other information which he is managing.
After receiving the request to access the desired information, the CPU of the controller 42 preferably communicates with the network-enabled optical storage and retrieval device cartridge retrieval arm 45 through an SCSI interface, and the server software sends instructions to the cartridge retrieval arm 45 to move the optical disk cartridges between the storage slots 46 and the optical disk drive 47 for read and write operations. An application in the optical storage and retrieval device server maintains a list of the status of the disk cartridges located in the optical storage and retrieval device, and, as indicated above, can also maintain directory pointers to off-line optical disk cartridges. Once the selected optical disk cartridge(s) 48 are moved to the optical disk drive 47, a workstation can access any information stored therein.
Although, as stated previously, network-enabled optical storage and retrieval devices 40 may hold, for example, as many as twenty optical disk cartridges, often times workstation users will desire access to a disk which is not loaded in the optical storage and retrieval device. If the workstation attempts to access information from a disk which is not currently loaded in the network-enabled optical storage and retrieval device 40, the workstation user will be required to manually retrieve the desired disk cartridge from the warehouse or other off-line storage area and substitute the desired disk for a disk which is currently loaded in the optical storage and retrieval device.
As stated previously, users of erasable optical media generally require substantial libraries of erasable optical disk cartridges, and thus generally organize and store these disk cartridges off-line in warehouses or other storage areas for retrieval at some later desired time using a labeling method, such as discussed above. However, due to such substantial number of disk cartridges, it becomes a tedious and laborious process of locating a desired off-line disk cartridge within the storage area. Additionally, when a disk is removed, it is often cumbersome to replace it in its proper location, particularly if other disks have also been removed, thereby creating a number of available/potential storage slots for the disk. This tedious and cumbersome process is exacerbated in the case of the network-enabled optical disk storage and retrieval device, given the fact that as more workstations, and thus users, have access to the network-enabled optical storage and retrieval device, more optical disk cartridges are likely to be exchanged, thus requiring users to make more trips to the optical disk cartridge storage area. Furthermore, as workstations are often remote from the optical disk cartridge storage area, the problem of readily located the desired optical disk cartridge becomes even more laborious and cumbersome. Similarly, the problem of replacing the optical disk cartridge in its proper location after it is has been used increases as the number of optical disk cartridge exchanges increases. External labeling, such as suggested above for magnetic cassettes, is insufficient as generally the workstation user is remote from the optical storage and retrieval device server, and will generally not know the alphanumeric code previously assigned to the optical disk cartridge(s) which he desires. Thus the user will have to determine from some sort of listing, the particular alphanumeric code for the optical disk cartridge(s) he desires before traveling to the storage area to retrieve same. As the number of optical disk cartridges increases, and the workstations become more remote, a substantial amount of time and energy will be unnecessarily expended.
It would therefore be desirable to provide a system for efficient off-line management of the optical disk cartridges so that a user could readily locate a desired disk from a storage library and replace said disk upon completion of use of same.
Accordingly, it is one object of the invention to provide a system and method of off-line management of optical media.
It is another object of the invention to provide a system and method of storing and retrieving optical disk cartridges from a storage area.
It is yet another object of the invention to provide a system and method of storing and retrieving optical disk cartridges which allows a user of an optical storage and retrieval device to readily locate a desired disk cartridges from a storage area and replace said disk upon completion of use of same.